Embodiments of the inventive concept relate generally to electronic memory technologies. More particularly, embodiments of the inventive concept relate to phase-change memory devices, and techniques for reading and writing data in multi-level cell phase-change memory devices.
Nonvolatile memory devices come in a variety of forms, including read only memory (ROM), electrically erasable programmable read only memory (EEPROM), flash memory, and phase-change memory, to name but a few. These and other types of nonvolatile memory have been under constant development in recent years in efforts to improve their storage capacity, operating speed, reliability, and other characteristics.
One area of development in nonvolatile memory devices involves storing larger amounts of data in individual memory cells. As examples, certain flash memory devices and phase-change memory devices have been designed to store multiple bits of data in each memory cell. Such devices are referred to as multi-level cell (MLC) nonvolatile memory devices, e.g., MLC flash memory devices, and MLC phase-change devices.
Although storing multiple bits per memory cell can improve the storage capacity of certain nonvolatile memory devices, it can also complicate program and read operations in a variety of ways. For instance, it can increase the amount of time and power required to perform the read and program operations, and it can decrease the reliability of the read and program operations. Consequently, researchers continue to explore ways to improve the operating characteristics of MLC nonvolatile memory devices.